Electric connecter plug



May 21, 1935. HY'lsSTRONGSON 2,002,302

ELECTRIC CCNNEQTER PLUG Filed Feb. 26, 1552 INVENTOR BY HEM/m L. ,5 mar/050,1

Patented May 21, 1935 ELECTRIC CONNECTER PLUG Herman L. Strongson, New York, N. Y., assignor to Beaver Manufacturing Company, Newark, N. 1., a corporation of New Jersey Application February 26, 1932, Serial No. 595,292

Claims.

This invention relates broadly to terminal members for electrical conductors and more particularly to improved means of construction for electrical attachment plugs of the flexible variety.

5 The subject matter contained herein constitutes an improvement in the construction disclosed in my prior Patent No. 1,780,851.

Although the present invention is adapted for.

use with electrical plugs of the rigid or frangible type, it is more particularly adapted to be used with electrical plug caps made from yielding, insulating material having a high degree of elasticity and resiliency, such as rubber. It has been customary in the prior art in attachment plugs of this type, to rigidly anchor the attachment prongs in the body itself, or to Permanently fasten the prongs to an insulating disc. Contact prongs are often subjected to rough usage which frequently results in tearing away of the prongs from their anchorage, or in destruction to the binding fiber disc, with a consequent loss in usefulness of the entire plug. By the present method of construction, it is possible to eliminate this contingency thus greatly increasing the effective life of the device. I

The principal objects of the present invention are to provide an electrical plug offering a large measure of protection against breakage, which will permit assembly at a minimized cost and which will permit the replacement of defective or damaged parts.

Further objects of the present invention are to eliminate all permanent fastening devices and to provide a construction which firmly binds end portions of the connecting wires, thereby relieving the stress at the contact terminals. Further objects and advantages of the present invention will be evidentfrom the following detailed description and from, the accompanying drawing, forming a part thereof, wherein Fig. 1 is a plan view showing a complete assembly of a preferred form of the invention.

Fig. 2 is a. plan view of the cap with the insulated disc removed therefrom.

Fig. 3 is a plan view of the preferred form of molded body.

Fig. 4 represents a plan view of a contact member with the prong bent at right angles to the base. 5 represents a preferred form of the insulatin'g disc. I Fig. 6 is a view similar alternate form.

Fig. 7 isa plan. view similar to Fig. 1, showing to Fig. 5, showing an the alternate form of insulating disc in assembled position.

Fig. 8 is a cross-sectional view through the insulating disc, taken on the line 88 of Fig. 6.

Fig. 9 is a cross-sectional view taken on the 5 line 9-9 of Fig. 1.

Fig. 10 is a longitudinal cross-section taken on the line lI-Hl of Fig. 1.

Fig, 11 is a cross-sectional view of the body taken on the line llll of Fig. 3. 10

Fig. 12 is an elevational view of a modified form of the contact member, showing the downwardly depressed tongue.

Fig. 13 is a plan view of the modified contact member.

Fig. 14 is a plan view of a modified body adapted to be used with the contact members represented in Figures 12 and 13.

Fig. 15 represents a blank of the contact member before the prong has been bent at right an- 20 gles to the base member.

Fig. 16 is a cross-sectional view similar to Fig.

10 showing the alternate form of insulating disc, in the mounted position.

The improved attachment plug comprises a 25 body Ill, preferably of flexaible elastic insulating material, such as rubber, and is provided with a central aperture l l to provide for passage of the electrical connecting wires. The body is preferably of conventional design, modified only in 30 such respects as to permit incorporation of the novel features. The upper portion of the body is recessed in the usual manner and is provided with an annular groove I! at a convenient distance below the upper margin of the plug, to 35 form a bead about the inside of the recess. The base of the recessed portion is flush with the lower wall of the annular groove as shown in Figure 11, and is channeled as at H, to provide depressed mounting of the contact members. This chan- 40 nel II is contoured to conform with the bases of the contact members and is preferably of slightly less depth than the thickness of the contact base member, to insure more rigid binding.

The contact member I! is of substantially seg- 45 mental shape and is preferably stamped from a piece of metal in the general configuration indicated in Figure 15. A contact prong ii of conventional design is bent at right angles to the contact base H, to form a generally L-shaped 5 structure. The contact base I1, is contoured to conform to the periphery of the groove H. A disc ll, formed of insulating material and pref erably semi-rigid sheet fiber, is apertured as at I. to permit insertion of the contact prongs when 55 in assembled position. The contact prongs are apertured and threaded to receive a conventional contact terminal screw 2@. Recessed holes 25, provided in the base, permit insertion of the stems of the contact terminal screws 20. A central aperture 22 in the disc permits the insertion of a suitable instrument for adjusting the contact screws.

An alternate form of disc is shown in Figure- 6. The cap of the contact screw used with this form projects above and binds against, the upper surface of the disc, as shown in Figure 16, and a pair of diametrically opposite apertures 26 are provided for the insertion of the screw stems. The disc i8, is of sufficient rigidity to form a binding and protective covering for the contact base members, and is of greater diameter than the inner diameter of the recess in the body, but of slightly greater thickness than that of the annular groove I2 formed in the walls of the upper recess. .Thus, it will be seen that by virtue of the resilient and elastic nature of the wall of the plug body, the disc may be forced into the annular groove, at the same time pressing the bases of the contact members into their respective recessed channels, after which the walls will contract and bind the disc in position.

In assembling a preferred form of the invention shown in Figure 1, contact members 15 shown in Figure 4 are each provided with a contact terminal screw 20. The stem of the screw is inserted in the hole 2|, formed in the body, and the entire contact base pressed into the recessed channel it shown in Figure 3, until the contact members are substantially flush with the face of the recess as indicated in Figure 2. The insulating disc is then placed over the contact prongs and pressure is applied in a downward direction, until the disc is securely bound in the annular groove, as shown in Figure 9. By making the groove ll of slightly less depth than the thickness of the contact base member, the body material will be compressed slightly before the bases of the contacts become flush with the face of the upper recess. When the disc snaps into the annular groove it will firmly hold the contact bases in this position, tightly compressed between the disc and the flexible body material without the use of permanent fastening devices. Sufflcient resilience is imparted by the flexible body material to the contact bases, to maintain the prongs in normal parallel relationship.

By this construction, perfect security and resilience of the prongs is insured without the use of permanent fastening devices, thereby facilitating replacement of parts, and minimizing the possibility of damage. If the prongs are subjected to disruptive forces which distort the contacts from their normal position, a lever action of the bases will cause the flexible walls to yield and permit the disc to become disengaged from its bound position, thus minimizing the possibility of damage to either the prongs or the plug base. In the event of damage to any member of the plug, replacement parts may easily be fitted into place to restore the entirety of the structure.

The connecting wires are inserted through the central aperture H, and in accordance with general practice, passed around the contact prongs and thence to the respective terminal members 20. The wires are preferably connected to the terminals before the disc I8 is snapped into place so that a portion of the wire will be compressed between the disc l8 and the base member II. The friction exerted on the wire by these two memhere will greatly alleviate pressure tending to aooasoa pull the connecting wire from the cap of the connecting screw 2@.

The assembly of the base plugemploying the modified form of disc shown in Figure 6 is similar to the assembly of the preferred form with the exception that the contact screws 2t may be placed in position after the disc has been inserted in the annular groove. If desired, the contact members may first be fastened adjacent the flexible disc by means of the screws 20 and the joined parts inserted in the base it as a unit, to form the assembly shown in Figure '7. Replacement of any parts may be effected by removing the contact screws 20 and expressing the disc ill from its bound position in the grooved wall of the base W.

In Figures 12 and 13, is shown a modified form of the contact members. The pointed end of the base member It is turned down to form a projecting tongue 24. This form of contact is preferably used with a base'member which has been provided with recessed slots 25, shown in Figure 14, adapted to receive the projecting tongues 24 of the contact members. These recessed slots in conjunction with the grooves l4, aid in preventing undesirable motion of the contact members relative to the base.

By the construction herein disclosed, it is possible to completely assemble a base plug without the use of permanent fastening devices. The elimination of riveted connections results in a reduction in the cost of machinery, maintenance and operation. In the preferred form shown in Figure 1, the entire assembly is maintained in normal relation by the bearing pressure of the disc l8 against the bases of the contact members l1. The disc I8 besides binding the parts in correct position and compressing the connecting wire against the base portion [1, also provides a substantially complete protective mask for the contact members and the terminals.

If the body I!) is subjected to disruptive stresses tending to forcefully remove the contacts from their secured position, as by pressure against the prongs, the contacts, by lever action, will cause the flexible walls to yield, and the entire structure will become released from its engaged position. Thus, it may be seen that the device is practically indestructible. 'Theabsence of permanent fastenings eliminates the possibility of damage, such as might be caused by forces acting on permanent anchoring means molded in the base, or fastening devices connecting the base members of the contacts with the insulating disc The forces holding the contacts in normal position are well distributed over the entire area of the contact base and thus greatly reduce pressures which otherwise would be localized at the small area occupied by a permanent fastening device.

The forms herein shown are merely illustrative of preferred embodiments of the present invention and are not to beconstrued in the limiting sense.

I claim:

1. An attachment plug comprising a body member of elastic material recessed at its upper portion, and provided with an annular groove in the wall of the recessed portion, an insulating disc of thin stifi material engaging the walls of the annular groove, said disk being provided with apertures, contact members having base portions resting against the base of said recessed portion in said disk, said contact members being held in substantially rigid position by bearing pressure of the insulating disc.

2. An attachment plug comprising a body member of elastic material recessed at its upper portion, provided with an annular groove in the walls of the recessed portion and with channels in the base of the recessed portion, contact members having base portions of the same configuration as the channels in the base of the recessed portion, an insulating disc of thin material peripherally engaging the walls of said annular groove, said base portions of said contact members being inserted in said channels and being maintained therein, in substantially rigid condition, by bearing pressure of the insulating disc.

3. An attachment plug comprising contact base members, contact prongs extending from said base members, an elastic body recessed at its upper portion, provided with an annular groove and with recessed channels shaped to receive said contact base members, an insulating disc of thin stifi material apertured to receive said contact prongs, said disc peripherally engaging the walls of said annular groove to retain the disk in said recessed portion, said contact base members being substantially rigidly held in said recessed channels by bearing pressure ap plied by said insulating disc.

4. An attachment plug comprising a resilient body recessed at its upper portion, and provided with an annular groove and with channels in the base of said recessed portion, contacts comprising upwardly extending prongs and base members, said base members being seated in said channels, terminal screws, an insulating disc of thin stiff material apertured to receive said prongs and head portions of said terminal screws, said disc peripherally engaging the walls of said annular groove to hold said contacts in position, with the base portions thereof between the body and the disk.

5. An attachment plug comprising a body member of elastic material recessed at its upper portion, providedwith an annular groove in the walls 01 the recessed portion, an insulating disc of thin stifi material adapted to peripherally engage the walls of said annular groove, contacts comprising upwardly extending prongs and base members seated in the recessed portion, terminal screws threaded into apertures in said base members, said disc being apertured to permit insertion of the prongs and being apertured to permit access to said terminal screws, said contacts being held in substantially rigid position solely by pressure exerted on the base members by the insulating disc, and without the use of permanent fastening devices.

HERMAN L. STRONGSON. 

